Orion’s Stellar Incubator

This nebula is alive with stars

By J. Alex Knoll

As the sun sets, one of the first constellations to appear is Orion, already high in the southeast, and by 8pm looming in the south. With its geometric, hourglass shape, Orion is one of the easiest constellations to spot and one of the most rewarding to study. The brightest star is blue-white Rigel to the lower right, marking the hunter’s left knee. Opposite to the upper left is the red-giant Betelgeuse, punctuating Orion’s raised right arm.
Marking the hunter’s opposite shoulder is Bellatrix, meaning female warrior. While nowhere near as bright as Rigel or Betelgeuse, Bellatrix is still the 22nd brightest star. Juxtaposed to the constellation’s lower left and marking the hunter’s right knee is Saiph, bright enough to stand up to the glare of this week’s bright moon.
Perhaps even more recognizable are the three almost perfectly aligned stars of Orion’s belt, Alnilam, Mintaka and Alnitak. The belt points down toward Sirius in Canis Major, the brightest of all stars. Following the belt the other direction leads to Taurus the bull and its red-orange star Aldebaran.
Hanging perpendicular from the belt is another, fainter line of stars that forms Orion’s sword. One of the objects in the sword isn’t a star at all but rather a blazing and massive illuminated cloud of stellar gas, the Orion Nebula, or M42. At 1,400 light years distant, the Orion Nebula shines at fourth magnitude, appearing as a fuzzy patch to the unaided eye. Binoculars reveal M42’s light as distinct stars, while even a modest telescope hints at the vast number of stars lurking within the clouds. But what really stands out is the luminosity as opposed to individual points of light. Nestled within the clouds like a celestial incubator are thousands of nascent stars, their light diffused and spread through the gas. The beacon of light above Orion is Jupiter. It is visible all night before finally setting in the northwest around 4am. Mars rises around 10:30pm and is high in the south around 3am. Saturn rises after midnight, well to the left of Mars and high in the south with dawn. By that time Venus is well positioned above the east horizon, having risen around 4:30. There’s no missing this morning star, unless you mistake it for a plane or some other unidentified flying object.